“The surest way to corrupt a youth is to instruct him to hold in higher esteem those who think alike than those who think differently.”
German philosopher Friedrich Nietzsche, famous for his work Thus Spake Zarathustra which introduces the idea of the Übermensch or superman, cautions that dismissing conflicting ideas by esteeming those that promulgate them as less worthy of our esteem than those with whose ideas we agree is the surest way to corruption. By corruption he means in the sense of a decay or retardation of the faculties of reason and of the internal moral compass which is strengthened through testing and reasasertion by reason and intellectual argument.
Thus the corruption of youth and the impressionable mind is most swiftly achieved by failure to give those who challenge the beliefs of youth the credence they deserve and dismissing the challenging notions out of hand because of a bias against those expressing those ideas.
This fits well with Nietzsche’s Teutonic background and his tendency to subject concepts to rigorous testing before accepting them.